Lifting and propelling device for aircraft



Jan. 13., 1925.

C.' H. KEEFER LIFTING AND PROPELLING DEVICE FOR AIRCRAFT Filed Dec R m wATTORNEY.

Patented 13, 1925.. I

UNirensures BI. KEEFER, or wasn'rneron, ms'rn cr or COLUMBIA.

LIFTING AND PBO'PELLING DEVICE FOR AIRCRAFT.

Application filed December 13, 1923. Serial No. 680,498.

opposite face of the body,

acter wherein the pressure of airinfront of or above a body is reducedto thereby permit the static atmospheric pressure to act on the body topropel it or lift it.

This invention is based on the fact that motion is the result ofunbalancedforces and that, therefore, if atmospheric pressure can bereduced on one side of ,a body, allow.- ing the static pressure to actagainst the if the difference in ressure is greatenough toovercomeinertia, it will cause the body. to-move for- 'ward" or in thedirection ofthe reduced pressure 1 -Tt has heretofore been proposed totake advantage of this difference in pressure surface.

' ward over} andclos'ely contiguous to and parallel w-ith a more or lessplane anterior I hare found by. experiments, however, that this will notcausea suflicient reduction of'press'ure on the anterior face of thebody or aerofoil as to cause tionof the body under the action of thestatic pressure behind it,. and" my. expen-v ments have demonstrated, onthe contrary,

that in order to cause a positive reduction;

of pressure on the anteriorface of-the-aerofoil or other body and aforward movement of the body through the 'aerofoil at an angle-t0 thefaceof what may be termed the entering or lead ng edge of the aerofoilto thereby cause the stream to be. deflected in its direction of flow,and

mayimpinge against the aerofoil at its 1ea d ing edge and be'dischargedin a stream or mass over the face of the aerofoil'and this will cause areduction'in pressurein front of aeronautics, and to propelling andlifting means for heai'rier-than-air machines of that charforcing astream of air to flow out-' the moy space that the; stream 'of airmustbecaused to impinge the body or aerofoil sufiicient to cause thestatic atmospheric pressure against the posterior face of the aerofoilto urgeit forward or upward.

It might be supposed that a fiuid stream having a direction angular tothe surface it strikes would rebound or be reflected at an angle equalto the angle of incidence. This would be probably true, for instance, ifthe stream is direct'ed through a fluid of, unlike density, thus, forinstance, if a jet of water is directed through air against a surface,but it is not the case where a fluid stream isset up in the midst ofordischarged through a likefluid, as an air stream set up in a massofair. Such a fluid stream impinging against a body at an angle theretoclings to the surface of the body against which it is impinged. Thispressure of the air which, therefore, forces the stream against thesurface of the body and holds it thereto. This stream will follow thesurface until it comes to an angle tendency to'be reflected is resistedby the Figure 1 is a fragmentary section of the anterior end of anaircraft, the propelling means therefor being shown in section, thefigure showing in dotted lines the manner in which an air stream will beprojected against the annular aerofoil and showing the manner in whichan area of low pressure will be formed in advance of the pro.- pellingmeans and of the aircraft;

Figure 2 is a fragmentary side elevation of the construction showninFigure 1;

Figure '3 is a fragmentary perspective view of this construction; I

Figure 4 is a top plan view showing the I general shape of the machineand indicating the manner in which the static acts to carry the machineforward.

In-these figures, 10 designates the body as, for instance, the body ofan aircraft having a'general streamline form and-carrying a motor (notshown) and steering means (notshown The forward end of the body is'soshape as to providean annular aerofoil 11 preferably convex, thevtrailing edge of the 'areofoil merging into the outer surface ofthe-more or less cylindrical body 10.

Extending through the-forward endof the body is a shaft 12, which iseither the motor shaft itself or a shaft driven therebyr Carried on thisshaft is a rotatable or centrifugal fan, designated generally 13. Theblades 14 of the fan are preferably radial and the extreme diameter ofthe fan is equal to the internal diameter of the aerofoil. The centralportion 15 of the forward end of the body 10 is preferably outwardlybulged or convex and the shaft passes through the apex or most'protuberant portion ofthis convexly bul ed end.

The blades 14 of the fan are'prefe'rably approximately triangular inelevation, the base of the triangle approximating the face of the.central portion 15. The outer corner or 'apex of each triangular bladeis rounded off. 'Thus the forward edge 'ofthe blade extends radiallyoutward at right angles to the axis of rotation, then curves outward andrearward, and then extends longitudinally parallel to; the" axis and atright angles to the leading edge of the aerofoil. A plate 16 may beattached to and from the bottom wallof the fan so as to cause the' airtomove inward as well as laterally.

Suitably supported on the body 10 in spaced relation to its forward end"is an annular.v fan casing '17 having a curvature approximately thecurvature given to the corners ofthe fan blades. The centralopeniug 18of this casing? constitutes the fan intake opening andthe peripheralopening 19 between the inner edge of the casing and the leading edgeofthe aerofoil constitutes the discharge opening. Of'c'ou'rse, the faceof the central portion 15. or the bottom wall indicated by the dottedlines and then is forced outward at a high speed against the aerofoilsurface. As a'consequence there. is

a-reduction in pressure n front of the body .of the body immediatelybehind the 'aero- .as possible.v

. It will be seen that the highest-velocity of the air stream isadjacent to. the "plate. I

foil surface. Preferablythe'. body tapers toward its rear-end in themanner indi cated so as to eliminate turbulence as, much.

16 and the lowest velocity of the air stream is adjacentto "the innerface ofthe fan cas.

ing.v This .is for the reason thattheair. stream has to travel atthesame radial speed along the base line of the triangular blades asit hasto travel adjacent theou-ter corners of the blades. Tl'ierefor'e the airwhich is caused. to directly impinge'against the leading edgeof theaerofoil surfaceistraveling at a very high speed; The shape of the fan 4causes a relativelv-thick stream of air toil be discharged fi cim thedischarge opening.

of the fan constitutes in effect part of the fan casing. The manner inwhich this mechanismoperates to produce a reduction in pressureforwardof the body 10'is shown" clearly by the dottedlines in Figurel, whichillu'sa. I rounded fuselage of the body 10 until-it trate approximatelythe, air flow to a centrifugal fan. The fan" draws the ,air from infront of it, both directly in front and laterally, and discharges thisair rearward and outward in lines diagonal to the axis of the body andin an annular'stream which impinges against and at an *angle' to theannular' face of the leading edge of the' reachesthe rear end thereof.

As'before remarked, the air in front of i the body and particularly infront of the fan is drawn centrally and toward the fan.-

of the fan toward and over the. aerofoil surface, and I have discoveredin actual practice that" it particularly advisable to have this stream'of air relatively. deep or thick and that th deeper the stream of airwithin- -'certain 1i its thefgreater the. pro- 1 pulsive effect.

Byusing a centrifugal fan so designed as to draw a'stream'of air to itscenter atthe front and discharge this stream radially over the surfaceof the aerofoil, I secure'a reductionin pressure at the front of the fanas well as a reduction in'prssure over'theface of ,the' aerofoil.Laboratory'tests with an. aerofoil and a fan constructed a as idescribed have shown a reduction in pressure of 224.5 pounds perhorsepower. of energy expended. This is more than fivetim es greaterthan the theoretical limit of 44 pounds per horse I power for standardtype propeller aero-foils and is nearly .66.times as great as the 3.43pounds perhorsepower developed by the propeller used on-the Martinbomber.

As beforeremarked, I have found by experimen't that the thicknessofthestratum or stream of air flowing .over' the aerofoil has animportantaffect on-the lifting value of -the aerofoil. For instance; ona six-inch annufour-inch aerofoil, it is apparent that a stream inchthick will give a liftfsom'elar aerofoil with an air stream of .12 of anfinch-1s thickness, a certa n llftval-ue. was 010- was found to lie-16times as great. By deduction from. the results obtained with a wherebetween 64 and 96 times the lift obtained with the .12 inch stratum.

The rapid passage of the air downward over the bottom plate of the fancreates an area of low pressure adjacent the plate and this aids themovement of the'air toward the areofoil and causes all-of the air infront of the fan to seek this low pressure area, or in other words toflow in a stream contiguous to the face of. the aerofoil;

While I haveheretofore referred to this propelling means as. .bein'particularly adapted to the propulsion of aircraft, I do not wish to belimited to this as it is obvious that the means which I have describedmight be used for the propulsion of submarines, or in other words thatthis propelling device is adapted to be used'wherever a. craft of anykind is entirely immersed in a fluid, whether this fluid be air, wateror any other gas or liquid, and it is to be understood that under thesecircumstances the term aerofoil isiconsidered throughout thespecificationas broad enough to cover any surface having the generalform of an aerofoil and against which fluid reacts in the mannerindicated for the reaction of airagainst an aerofoil on. alighter-than-air machine. be understood that the same principle might beused for the propulsion of water craft where a part of the hull issubmerged or almost entirely submerged and, therefore, can have thestreamline form having a'foi-l or surface of like character at itsforward end against. which the fluid may. be caused to impinge.

While it before stated, to reduce the pressure of fluid in front of anaircraft by the provision of means driving an annular stream of airoutward in all directions in close contiguity to the surface of theaerofoil, yet, as before is impossible for this to work propstated, iterly unless the an is caused to impinge against a portion of saidsurface at an angle thereto so as to thereby deflect the air. Thus in aconstruction of this proposed. character, it is impossible tosecureany-reduction in ress'ure in frontof the aeroplane or'other b( which.will be suflicient to cause tlv static pressure to drive the machineforward. The reason for this is that where the air stream is forcedoutward :contiguous'to a surface more or.less at right 'anglesto theaxis of' the machine. and without the air.

stream impinging against the-aerofoil and being deflectedthereby, theair stream, while it causes a very slight low pressure area in front ofthe machine, also causes this air to be drawn from all directions andthus c0un- I teract the action of any low pressure area in front of themachine. In this present invention, because the air stream followsaround the streamline form of the body being propelled, it is the bodyitself which is' ."of the body.

It is also to has "heretofore been proposed, as

fed into the low pressure area bythe static I pressure of air em-g fedinto this low pressure area.

fluid at high velocity to move rearwardly behind it insteadlof the airand radially outward from a point in ad-,

vanc'e of'the body 1 and impinge against" theforwardly exposed, anteriorfaceof tlie body at an angle to the face and to the fore and aft axis ofthe body to thereby cause a reduction in the static air pressure infront -2. body having an anterior, annular, cambered forwardly exposedsurface,

rearwardly and radially outwardly in all directions froma point inadvance of said surface at and against the? leading edge bf at a-highspeed over said body. a

3. A flying machine having an-annular, anterior, cambered, forwardlyexposed sur- .means for discharging fluid under pressure face, and meansfor causing air under pressure to be discharged rearwardly and radial-'ly outward in all directions from a point .in advance of said surface atan angle to the fore and aft axis of the body and against the leadingedge of the cambere'd surface and at an angle tliereto to thus cause theair to flow at a high ,speed' over said surface to. thereby reduce thestatic atmospheric pressure in front thereof. a

4. A body having a substantially annular,

anterior, forwardly exposed, fluid-receiving surface defining a surfaceconcentric to the line of flight and tapering toward. the direcfli ht,and means for projecting af tion of stream of fluid at a high velocityrearwardly and radially-to the longitudinal axis of the] body from apoint in advance, of said surface at an angle to the fore and aft axisof thebody against said surface andat an angle thereto.. 5. A bodyhaving a substantially annular, anterior, forwardly exposed,fluid-receiving surface, said surface being concentric to-tlie taperingtoward the di- -reetion of flight, and means for} projecting .astream'of air rearwardly. from a point line of flight and in advance ofthe surface and radially in all the fan and .pro

velocity outward -and rearward at an "angle directions at a highvelocity against" said surface and -at an obtuse angle thereto.--'

6.. A .body'movable through space and inf eluding an annular anteriorlycambered, for,-

i sure on opposite faces of a body-including an anterior, forwardlyexposed, annular surface carriedbythe body,-the anterior face ofentering edge ofthe surface being cambered', and means for delivering astream of air athi-gh velocity outward and rearward at an angle to the,fore and-aft axis of thebody and against the the *camberedsurface at anangle to the point on the surface against which the. air is projected tothereby cause the said fluid stream to flow in' all directions over andin close contiguity with'said face j of the body-.1

20' exposed-surface: and means body through space including motor op-.erated-means carried by, the

'8. A bodyhavingan' anterior, forwardly for i mdvingth bod-y fordisplacing theair in-advance of the body and projecting the air' sodisplaced rearward in a stream at an angle to thefore and aft axis ofthe-body and against .the anterior or less'than a right angle surfaceand at an'angle to-"the same thereof rearwardly and radially directions.to thereby causethe air to'flow at' a higi velocity radially in alldirections over an in close contiguity with i the anterior face of thesurface;

v the bodyzthroughs ace exposed,

body of said cambered face.

9( A body having an anterior,- forwardly annular surface having anannular' camber, the face of the body beyondsaid camber beingconvexlyrounded,-'and means for moving the ing means carried by the body anddisposed concentriciall within the annular cambered 'portionjfor rawingthe fluid in advance of) the body toward the body and projecting thefluid rearwardly and radially rearward at an angle to the fore and aftaxis of the agamst'said cambered face, the leading edge deflecting thefluid stream discharged'thereagainst.

10. -A:body including an anterior annular surface havm a camberedanterior forwardly expose face, and means for moving including-a motoroperated centrifuga fan. disposed ,at the a center of and concentric tothe annular sur fluid continuously le t0 the against face, the fandischarging. at its periphery rearward at an an fore and aft axis-of thebody an I the cambered face,'-said cambered face being her bein 4 movingt e body through space including a soplaced that its leading edgedeflects the" fluid stream discharged by said fan.

11'. A'body having an anterior, annular, forwardly exposed surfacehaving an annular camber, the surface beyond. said camrelatively .flat,and means for the body and annular camber,

"and at an angle to said cambered face, leading edge of the cumbcredface deflectmg ;of.said cambered less than a right angle.

I casing partially housing said shaft body through space includ-.

inall directions at a high velocity 'yond the motor operated centrifugaltan carried by disposed concentrically to the said fun drawing the fluidin advance of the body toward the body and projecting said fluid at ahigh velocity in all directions rearward at an angle to the fore and aftaxis of the body and against the fluid stream discharged by said fan.

motor operated means for causing a stream of air to be disclnirgedrearward at an angle to the fore and aft axis of the body, said meanscausing tluair against the anterior face of the leading edge surface atan angle thereto 13'. A flying machine including a forwardly exposed,anterior surface, the surface beto be discharged only the 12. A flyingmachine. having a cambered anterior forwardly exposed surface. and

ing cambered, and means carried-by the machlne for drawing a stream offluid from a point in advance of the machine toward the anterior face ofthe surface and projecting the stream-of fluid at a high velocityradially outward and rearward in all-directions at an angle to the andat an angle to the face of the surface less-than a right angle, theleading edge of the aerofoil deflecting the fluid stream.

14. A flying machine including a fuselage having a generalstre'amhneform, a motor fore and aft axis of the body operated shaft projectingthrough the forward end of the fuselage, a centrifu al' fan mounted uponsaid shaft, an annn ar fan and having a centrally disposed intakeopening, and a circumferentially disposed outlet opening,

the'fuselage having a diameterat its forward end greater than thediameter of the fan casing and that portion of'the fuselage beyond thefan casing being curved to form an anterior, annular,- forwardlyexposed, fluid receiving surface against which the air from the fan iscaused to impinge and by which said air is deflected.

15. 'A flying machine having a fuselage of general streamline form, ashaft extending through the fuselage and beyond its forward end,approximately triangular blades mountedvu on 'theshaft and rotatingtherewith, the blades having their bases extending rearward and outwardfrom the axial center of the fan to a point inward of the greatestdiameter ofthe there bein a floor extending along the bases of all of te. blades, a fan casing extending overthe blades and having a centralintake opening and aperipheral discharge opening, that portion of thefuselage projecting befan casing being convexly rounded to forma'cambered surface against which the air from the fan is discharged andby which theair is deflected.

forward end of-the fuselage,

16. In a flying machine, a fuselage, a shaft shaft extending through theforward end of extending through the fuselage and beyond the fuselagethrough the conical portion, trithe same, a plurality of approximatelytriangular blades mounted upon the shaft and angular blades attached attheir outerends rotating therewith, the blades having inner to saidshaft and extending rearward and edges extending downward and rearwardto outward, the corners of the blades being the base of said conicalportion, said conical rounded and there being a conical floor disportionconforming to the angle of the bases posed contiguous to the bases ofall of the of said blades, the outer corners of the blades blades, anannular casing transversely being truncated, an annular casingencl0scurved to fit the corners of the blades, said ing said truncatedportions of the blades, the w casing defining a central openingconcentric casing defining a central inlet opening conto the shaft and aperipheral opening, the centric to the shaft and a peripheraldisfuselage having a diameter greater than the charge opening, thefuselage having a diamdiameter of the fan and being rounded eteradjacent the fan greater than the diamto provide an annular camberedaerofoil eter of the fan and that portion of the fusel- 1 surfacemerging at its rear end into the age projecting beyond the fan beingformed fuselage and against which the air projected to provide anannular surface, the air from by the fan blades is directed and by whichsaid fan being driven outward and rearward said air is defiecte -inangular relation to the leading edge of 17. A flying machine of thecharacter dethe aerofoil, the surface extending rearward scribedcomprising a fuselage approximately and merging into the surface contourof the circular in cross section and having a genfuselage.

eral streamline outer surface, the forward In testimony whereof I affixmy signa end of the fuselage having an approximately ture.

conical central portion, a motor operated CHARLES H. KEEFER.

